The present invention relates to an image forming apparatus, such as a copying machine or a facsimile machine, provided with an image reading section and a paper switchback mechanism which can reverse the paper feeding direction.
Generally, the construction of a conventional image forming apparatus having an image reading section like a copying machine or a facsimile machine is such that the image reading section is provided in an upper portion of a main body of the apparatus and an image forming section is located in a lower portion of the main body, in which each sheet of paper carrying an image formed in the image forming section is ejected onto an output tray provided on one side of the apparatus. Nowadays, most image forming apparatus employ digital technology, and this has made it possible to position their image reading section and image forming section independently of each other.
In an image forming apparatus proposed recently, a paper output space for receiving each sheet of paper which has gone through an image forming process is provided between an image reading section in an upper portion of a main body of the apparatus and an image forming section in a lower portion of the main body, unlike the conventional image forming apparatus whose output tray is provided on one side of the apparatus. An important advantage of this approach is that the overall size of the image forming apparatus is reduced, making it possible to place the apparatus even in a limited space available.
In another recently proposed image forming apparatus, an image reading section provided in an upper portion of a main body of the apparatus is located toward the rear of an image forming section which is provided in a lower portion of the main body and there is formed an opening in the front of the apparatus at a position higher than a paper output space which is provided between the image reading section and the image forming section. This approach is advantageous in that it is easier to visually check each sheet of paper ejected into the paper output space and take them out from the paper output space. If the image forming apparatus of this kind is required to have a double-sided image forming capability, there is provided a switchback path inside the apparatus. A sheet of paper is temporarily led into the switchback path to undergo a switchback operation, in which the paper feeding direction is reversed and the sheet is turned upside down.
If, however, such a switchback path is provided in the main body of the apparatus, a paper jam is likely occur while the paper is obliquely transferred during the switchback operation. Nevertheless, it has been difficult in prior art constructions to remove the paper which has jammed in the switchback path.
It might be possible to use a space available at the side of the main body of the apparatus for temporarily holding the paper during the switchback operation. A problem of this approach is that proper switchback operation is likely to be disturbed if the paper, which is temporarily ejected to the side of the apparatus during the switchback operation, goes into physical contact with the body of an operator or other objects around the main body of the apparatus.
It is an object of the invention to provide an image forming apparatus which solves the aforementioned problems of the prior art.
According to the invention, an image forming apparatus comprises an image forming unit, a paper ejector for ejecting a sheet of paper carrying an image formed by the image forming unit onto a top surface of the image forming unit, and an image reader located above the image forming unit with a hollow space of specific dimensions formed between the image forming unit and the image reader, the hollow space serves to hold the sheet ejected onto the top surface of the image forming unit, a front surface of the image reader is recessed rearward from a front surface of the image forming unit so that a part of the top surface of the image reader can be observed from above the image forming apparatus, and the paper ejector includes a switchback mechanism for performing a switchback operation in which the sheet is turned to an opposite feed direction and guided back into the image forming unit after the paper ejector has advanced the sheet transferred from the image forming unit until a portion of the sheet projects over the top surface of the image forming unit.
Since the hollow space provided between the image forming unit and the image reader is used for temporarily holding the sheet of paper during the switchback operation in this image forming apparatus, an operator can catch a forward portion of the sheet projecting into the hollow space between the image forming unit and the image reader from above the apparatus and easily pull out the sheet to remove a paper jam. The construction of this image forming apparatus helps prevent physical contact between the paper and the body of the operator or other objects outside the main body of the apparatus during the switchback operation.